High-throughput screening (HTS) is a method for the rapid and accurate analysis of large numbers of chemical compounds for activity against selected targets. Typical chemical libraries contain hundreds of thousands to millions of separate compounds that are screened against a wide variety of targets. The large numbers of compounds that must be routinely screened has led to a requirement for new technologies capable of rapid and quantitative analysis.
Various types of analysis performed on samples are enhanced by first preparing the sample. In particular, mass spectrometry is a powerful technique uniquely suited for many HTS applications. Mass spectrometry allows accurate quantification of a compound based on its mass alone, eliminating the need for the development of specific spectroscopic assays. The current state-of-the-art mass spectrometers using atmospheric pressure ionization (API) interfaces are not compatible with samples in solutions that contain high levels of non-volatile salts or contaminants. Non-volatiles in the sample can cause both suppression of the desired sample signal and can cause the mass spectrometer to fail due to build-up of precipitates within the ion guide and inlet. Therefore, samples must be purified from non-volatile contaminants and desalted prior to analysis. Additionally, this must be performed, as discussed above, in a manner conducive to high throughput screening.